David,
most of my experience with relational databases is with Oracle. Oracle supplies two types of JDBC drivers, OCI and Thin. Since the OCI driver is a Type II driver, that makes use of native code, it might be natural to assume that it would give better performance than the Thin driver. My experience, however, is quite the opposite, especially if you obtain the latest driver edition (for 8.1.7). In addition, it is generally more simple to develop applications with the Thin driver (you are not dependent on Oracle client software at the middle tier). However, there are cases where you must use the OCI driver, such as when using public synonyms through JDBC (doesn't work with Thin). So each type has its cons and pros that must be evaluated for each application in question.
For SQL Server, I have mostly been using the JTurbo JDBC driver from
http://www.jturbo.com. But, as I said, I don't work that much with SQL Server in the enterprise, so I don't really have any comparison there.
Cheers,
Bjarki
[This message has been edited by Bjarki Holm (edited June 12, 2001).]